Electrical pick-up apparatus



Oct. 1934. c K'ENTNER 1,978,583

ELECTRICAL RICK-UP APPARATUS Filed Nov. 14, 1951 I N V E 16R. Cqrro U.D. fi entner;

I- r HIQSATTORNEY. 2

Patented Oct. 30, 1934 PATENT OFFICE ELECTRICAL PICK-UP arrm'rus ICarroll D. Kentner, Collingswood, N. .L, assigncr to Radio Corporationof America, a corporation of Delaware Application November 14, 1931,Serial No. 574,961

' 6 Claims. (01. 84-408) My invention relates to improvements inelectrical pick-up apparatus l adapted, particularly,

for embodimentin electrical musical systems,'

such as electric carillons, chimes, pianos, and the like.

In systems of the character referred to, a single note is sounded bystriking a suitable vibratory member, associated with an electricalpick-up device. This member forms part of a magnetic circuit and, uponvibrating, causes a current wave to be developed in the pick-up coil,corresponding t0 the note to which the member is tuned. The

note is made audible by amplifying the current wave and supplying thesame to a loudspeaker.

In constructing an electrical musical instrument having a relativelylarge number 01 units to produce as many different notes, there is theproblem oi arranging and supporting the large number of pick-up devicesin a compact and convenient way without giving rise to a conditionwherein operation of any one device will, on account of its closemechanical association with the others, cause one or more of the same tooperate at least in some degree and, thereby, to produce an accompanyingand undesirable note along with' the particular note being sounded atthe time. This undesirable eflect has been attributed to the mechanicaltransmission of. vibration from the operated device to one or more orthe others supported in close proximity thereto and to the phenomenon ofmutual inductance between adiacent device's. These difliculties increaseas the individual pick-up devices are arranged closer together to obtainthe best advantage in the way of compactness of construction.

with the foregoing in mind, it is one of the objects oi my invention toprovide improved pickup apparatus, 01' the character referred to, whichI comprises any desired number of individual pickup devices, thesupporting structure and the construction and arrangement of the variousparts of the individual devices being such that the same may be arrangedconveniently in bank formation and in close proximity to each other toobtain the best advantage as regards compactness and sime plicity ofconstruction while, at the same time,

preventing operation, in any eiiective degree, of

Figure 1 is a fragmentary, perspective view,

partly in section, oi. electrical pick-up apparatus embodying myinvention, one of the parts being removed;

Fig. 2 is an elevational view, partly in section, looking toward theright in Fig.1; and

Fig. 3 is a diagrammatic, perspective view of an electric carillonsystem embodying the pick-up apparatus shown in Figs. 1 and 2.

In Fig. 1, three of the pick-up units, constructed in accordance with myinvention, are designated, respectively, by the reference-numerals 10,11 and 12. These units, as shown, are arranged in row formation, spacedfrom each other, and are provided, respectively, with vibratory members13, 14 and 15 having different periods of vibration corresponding todifferent notes in the musical scale.

As these units are of identical construction, description of one willsuiiice for all. With reference, more particularly, to'Fig. 2, the. unit10 comprises complementary pole elements 16 and 17, having pole portions18 and 19. The pole elements 16 and 1'7 are secured. by bolts 16a and17a to a nonmagnetic supporting member-21. The pole elements areprovided with shoulders 22 and 23 which fit the adjacent edges 01' themember 21, whereby the latter acts as a gauge or spacing member to holdthe pole elements in fixed relation with their pole portions 18 and 19spaced properly to provide an air gap 241.

By reason or the close fit of the shoulders 22 and 23 with the edges ofthe member 21, the pole elements 16 and 17 are held against pivotal movement about the axes of the securing bolts 16a and 17a.

A pick-up coil 25 is disposed, as shown, be a For the purpose of holdingthe member 13 in flxedposition for tree vibratory movement withoutcontacting with thepole portions 18 and 19, the coil 25, or the edge oithe opening 29, an L-shape supporting member 9 is secured to the poleelement 1'7, for which purpose this member is tapped to receive thethreaded end of the bolt 170 which passes loosely through the member 21and the pole element 17. The tip 300! the end portion 28 is clampedbetween a block 81 and the member 9, for which purpose the latnected inparallel in the material.

ter is adapted to receive bolts 32. By unscrewing the bolts 32, thestraight, end portion 28 of the member 13 can be adjusted longitudinallyto change the period of vibration and therefore the note produced.

The member 13 is caused to vibrate upon being struck by a peg 33 ofsuitable nonmetallicmaterial, such as gut or wood, which rests upon acore 34 of magnetic material. These parts have a free fit in the centralopening of a solenoid winding 35, which, upon being excited, causes thecore to move almost instantly to the center of the winding, whereuponthe peg 33 strikes the member 13 sharply to cause the same to vibrate.

The member 9, the block 31 and the bolts 32 are made of brass or othersuitable nonmagnetic As shown in Fig. 1, the supporting member 21 iscommon to the units 10, 11 and 12, and supports the same in rowformation, adjacent units being spaced only a relatively short distancefrom each other to obtain the advantage of compactness.

The supporting member 9, also, is common to the various units, andoperates to support all of the vibratory members 13, 14 and 15.

A suitable horse-shoe magnet 36 embraces the member 9 and the associatedparts, as shown, and remains in position by reason 015 its attraction tothe pole elements 16 and 1'7.

For the purpose of utilizing my improved pickup apparatus in a systemfor playing a tune,

chimes, or any desired sequence of musical notes,-

the individual units may be connected as shown diagrammatically in Fig.3, wherein the pick-up coils 25, 37 and 38 of the units 10, 11 and 12,respectively, are connected in series, the series being connected asshown in the input circuit of a suitable amplifier 39. The amplifiedcurrent waves are caused to p'ass through the usual electromagnetiocoils40 of loudspeakers 41, conoutput circuit of the amplifier. i

The solenoid coils 35, 42 and 43 associated, respectively, with thevibratory members 13, 14 and 15, are each connected across a battery 44,through keys or switches 45, 46 and-4'7, respectively. Upon depressionof any one of the keys to complete the circuit, the associated solenoidcoil becomes excited to cause the corresponding vibratory member to bestruck and set into vibration, thereby changing the flux distribution inthe air-gap to induce a corresponding voltage wave in the pick-up coil.The note, corresponding to the period of vibration of this member, isthen sounded from the loudspeakers 41.

WhileI have shown but three of the units, 10, 11, and 12, it is proposedto mount any desired number of these units in row formation, as shown inFig. 1, the supporting members 21 and 9 being common to all. As before,the pick-up coils would be connected in series, parallel, orseries-parallel, with the input circuit of the amplifier, and therespective solenoid coils would be connected in the same manner as coils35, 42

and 43 in Fig. 3, a separate key or switch being supplied for each, andarranged with the others in the form of a keyboard for convenientoperation.

While but one embodiment of my invention has been disclosed, it will beunderstood that various changes might be made, such as in the size,shape and arrangement of the various parts, without departing from thespirit of my invention or the scope of the claims.

I claim as my invention:

1. In pick-up apparatus of the character described, a plurality ofpick-up units arranged in row formation and spaced from each-other, eachof said units comprising complementary pole elements having poleportions, a member of nonmagnetic material common to said units and towhich the complementary pole elements of each unit are secured with therespective pole portions held in spaced relation to provide air gaps,said member provided with openings opposite to the respective air gaps,vibratory members associated respectively with said units and. extendingfreely through said openings and said air gaps, and means supportingsaid vibratory members in fixed position for vibration free from saidpole portions and the edges of said openings.

2. In an electrical pick-up device,-complementary pole elements havingpole portions and supported with said portions in spaced relation toprovide an air gap, an elongated vibratory member having an end portiondisposed between said elements and extendingthrough said gap, and

means secured to one of said elements and hold respective air gaps,vibratory members associatedrespectively with said units and extendingfreely through said openings and said air gaps, and means secured to oneof said pole elements of each unit for supporting said vibratory membersin fixed position for vibrationfree from said pole portions and theedges of said openings.

4. In an electrical pick-up device, complementary pole elements havingpole portions and supported .with said portions in spaced relation toprovide an air gap, an elongated vibratory member having an end portiondisposed between said elements and extending through said gap, a sub--stantially L-shape support secured to one of said elements, and meansclamping the tip of said end portion to said support to hold said memberin fixed position for free vibratory movement from said tip.

5. In an electrical pick-up device, complementary pole elementssupported in spaced relation to provide an air gap, an elongatedvibratory member having an end portion disposed between said elementsand extending through said gap, a sup- 3 port secured to one of saidelements, and means clamping the tip of said end portion to said supportto hold said member in fixed position for free vibratory movement fromsaid tip.

6. In an electrical pick-up device, complementary pole elementssupported in spaced relation to provide an air gap, an elongatedvibratory member having an end portion disposed between said elementsand extending througl said gap, a pick-up coil disposed between saidelements and having a central opening through which said end portion ofsaid member extends, and a support secured to one of said elements andholding said member for free vibratory movement from said support to thefree end of said member.

CARROLL D. KENTNER.

